Pharmacokinetic modeling of [11C]flumazenil kinetics in the rat brain

Isadora Lopes Alves, David Vállez García, Andrea Parente, Janine Doorduin, Rudi Dierckx, Ana Maria Marques da Silva, Michel Koole, Antoon Willemsen, Ronald Boellaard

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

BACKGROUND: Preferred models for the pharmacokinetic analysis of [11C]flumazenil human studies have been previously established. However, direct translation of these models and settings to animal studies might be sub-optimal. Therefore, this study evaluates pharmacokinetic models for the quantification of [11C]flumazenil binding in the rat brain. Dynamic (60 min) [11C]flumazenil brain PET scans were performed in two groups of male Wistar rats (tracer dose (TD), n = 10 and pre-saturated (PS), n = 2). Time-activity curves from five regions were analyzed, including the pons (pseudo-reference region). Distribution volume (VT) was calculated using one- and two-tissue compartment models (1TCM and 2TCM) and spectral analysis (SA). Binding potential (BPND) was determined from full and simplified reference tissue models with one or two compartments for the reference tissue (FRTM, SRTM, and SRTM-2C). Model preference was determined by Akaike information criterion (AIC), while parameter agreement was assessed by linear regression, repeated measurements ANOVA and Bland-Altman plots.

RESULTS: 1TCM and 2TCM fits of regions with high specific binding showed similar AIC, a preference for the 1TCM, and good VT agreement (0.1% difference). In contrast, the 2TCM was markedly preferred and necessary for fitting low specific-binding regions, where a worse VT agreement (17.6% difference) and significant VT differences between the models (p < 0.005) were seen. The PS group displayed results similar to those of low specific-binding regions. All reference models (FRTM, SRTM, and SRTM-2C) resulted in at least 13% underestimation of BPND.

CONCLUSIONS: Although the 1TCM was sufficient for the quantification of high specific-binding regions, the 2TCM was found to be the most adequate for the quantification of [11C]flumazenil in the rat brain based on (1) higher fit quality, (2) lower AIC values, and (3) ability to provide reliable fits for all regions. Reference models resulted in negatively biased BPND and were affected by specific binding in the pons of the rat.

LanguageEnglish
Article number17
JournalEJNMMI Research
Volume7
Issue number1
DOIs
Publication statusPublished - Dec 2017

Cite this

Alves, I. L., Vállez García, D., Parente, A., Doorduin, J., Dierckx, R., Marques da Silva, A. M., ... Boellaard, R. (2017). Pharmacokinetic modeling of [11C]flumazenil kinetics in the rat brain. EJNMMI Research, 7(1), [17]. https://doi.org/10.1186/s13550-017-0265-4
Alves, Isadora Lopes ; Vállez García, David ; Parente, Andrea ; Doorduin, Janine ; Dierckx, Rudi ; Marques da Silva, Ana Maria ; Koole, Michel ; Willemsen, Antoon ; Boellaard, Ronald. / Pharmacokinetic modeling of [11C]flumazenil kinetics in the rat brain. In: EJNMMI Research. 2017 ; Vol. 7, No. 1.
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title = "Pharmacokinetic modeling of [11C]flumazenil kinetics in the rat brain",
abstract = "BACKGROUND: Preferred models for the pharmacokinetic analysis of [11C]flumazenil human studies have been previously established. However, direct translation of these models and settings to animal studies might be sub-optimal. Therefore, this study evaluates pharmacokinetic models for the quantification of [11C]flumazenil binding in the rat brain. Dynamic (60 min) [11C]flumazenil brain PET scans were performed in two groups of male Wistar rats (tracer dose (TD), n = 10 and pre-saturated (PS), n = 2). Time-activity curves from five regions were analyzed, including the pons (pseudo-reference region). Distribution volume (VT) was calculated using one- and two-tissue compartment models (1TCM and 2TCM) and spectral analysis (SA). Binding potential (BPND) was determined from full and simplified reference tissue models with one or two compartments for the reference tissue (FRTM, SRTM, and SRTM-2C). Model preference was determined by Akaike information criterion (AIC), while parameter agreement was assessed by linear regression, repeated measurements ANOVA and Bland-Altman plots.RESULTS: 1TCM and 2TCM fits of regions with high specific binding showed similar AIC, a preference for the 1TCM, and good VT agreement (0.1{\%} difference). In contrast, the 2TCM was markedly preferred and necessary for fitting low specific-binding regions, where a worse VT agreement (17.6{\%} difference) and significant VT differences between the models (p < 0.005) were seen. The PS group displayed results similar to those of low specific-binding regions. All reference models (FRTM, SRTM, and SRTM-2C) resulted in at least 13{\%} underestimation of BPND.CONCLUSIONS: Although the 1TCM was sufficient for the quantification of high specific-binding regions, the 2TCM was found to be the most adequate for the quantification of [11C]flumazenil in the rat brain based on (1) higher fit quality, (2) lower AIC values, and (3) ability to provide reliable fits for all regions. Reference models resulted in negatively biased BPND and were affected by specific binding in the pons of the rat.",
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Alves, IL, Vállez García, D, Parente, A, Doorduin, J, Dierckx, R, Marques da Silva, AM, Koole, M, Willemsen, A & Boellaard, R 2017, 'Pharmacokinetic modeling of [11C]flumazenil kinetics in the rat brain', EJNMMI Research, vol. 7, no. 1, 17. https://doi.org/10.1186/s13550-017-0265-4

Pharmacokinetic modeling of [11C]flumazenil kinetics in the rat brain. / Alves, Isadora Lopes; Vállez García, David; Parente, Andrea; Doorduin, Janine; Dierckx, Rudi; Marques da Silva, Ana Maria; Koole, Michel; Willemsen, Antoon; Boellaard, Ronald.

In: EJNMMI Research, Vol. 7, No. 1, 17, 12.2017.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Pharmacokinetic modeling of [11C]flumazenil kinetics in the rat brain

AU - Alves, Isadora Lopes

AU - Vállez García, David

AU - Parente, Andrea

AU - Doorduin, Janine

AU - Dierckx, Rudi

AU - Marques da Silva, Ana Maria

AU - Koole, Michel

AU - Willemsen, Antoon

AU - Boellaard, Ronald

PY - 2017/12

Y1 - 2017/12

N2 - BACKGROUND: Preferred models for the pharmacokinetic analysis of [11C]flumazenil human studies have been previously established. However, direct translation of these models and settings to animal studies might be sub-optimal. Therefore, this study evaluates pharmacokinetic models for the quantification of [11C]flumazenil binding in the rat brain. Dynamic (60 min) [11C]flumazenil brain PET scans were performed in two groups of male Wistar rats (tracer dose (TD), n = 10 and pre-saturated (PS), n = 2). Time-activity curves from five regions were analyzed, including the pons (pseudo-reference region). Distribution volume (VT) was calculated using one- and two-tissue compartment models (1TCM and 2TCM) and spectral analysis (SA). Binding potential (BPND) was determined from full and simplified reference tissue models with one or two compartments for the reference tissue (FRTM, SRTM, and SRTM-2C). Model preference was determined by Akaike information criterion (AIC), while parameter agreement was assessed by linear regression, repeated measurements ANOVA and Bland-Altman plots.RESULTS: 1TCM and 2TCM fits of regions with high specific binding showed similar AIC, a preference for the 1TCM, and good VT agreement (0.1% difference). In contrast, the 2TCM was markedly preferred and necessary for fitting low specific-binding regions, where a worse VT agreement (17.6% difference) and significant VT differences between the models (p < 0.005) were seen. The PS group displayed results similar to those of low specific-binding regions. All reference models (FRTM, SRTM, and SRTM-2C) resulted in at least 13% underestimation of BPND.CONCLUSIONS: Although the 1TCM was sufficient for the quantification of high specific-binding regions, the 2TCM was found to be the most adequate for the quantification of [11C]flumazenil in the rat brain based on (1) higher fit quality, (2) lower AIC values, and (3) ability to provide reliable fits for all regions. Reference models resulted in negatively biased BPND and were affected by specific binding in the pons of the rat.

AB - BACKGROUND: Preferred models for the pharmacokinetic analysis of [11C]flumazenil human studies have been previously established. However, direct translation of these models and settings to animal studies might be sub-optimal. Therefore, this study evaluates pharmacokinetic models for the quantification of [11C]flumazenil binding in the rat brain. Dynamic (60 min) [11C]flumazenil brain PET scans were performed in two groups of male Wistar rats (tracer dose (TD), n = 10 and pre-saturated (PS), n = 2). Time-activity curves from five regions were analyzed, including the pons (pseudo-reference region). Distribution volume (VT) was calculated using one- and two-tissue compartment models (1TCM and 2TCM) and spectral analysis (SA). Binding potential (BPND) was determined from full and simplified reference tissue models with one or two compartments for the reference tissue (FRTM, SRTM, and SRTM-2C). Model preference was determined by Akaike information criterion (AIC), while parameter agreement was assessed by linear regression, repeated measurements ANOVA and Bland-Altman plots.RESULTS: 1TCM and 2TCM fits of regions with high specific binding showed similar AIC, a preference for the 1TCM, and good VT agreement (0.1% difference). In contrast, the 2TCM was markedly preferred and necessary for fitting low specific-binding regions, where a worse VT agreement (17.6% difference) and significant VT differences between the models (p < 0.005) were seen. The PS group displayed results similar to those of low specific-binding regions. All reference models (FRTM, SRTM, and SRTM-2C) resulted in at least 13% underestimation of BPND.CONCLUSIONS: Although the 1TCM was sufficient for the quantification of high specific-binding regions, the 2TCM was found to be the most adequate for the quantification of [11C]flumazenil in the rat brain based on (1) higher fit quality, (2) lower AIC values, and (3) ability to provide reliable fits for all regions. Reference models resulted in negatively biased BPND and were affected by specific binding in the pons of the rat.

KW - Journal Article

U2 - 10.1186/s13550-017-0265-4

DO - 10.1186/s13550-017-0265-4

M3 - Article

VL - 7

JO - EJNMMI Research

T2 - EJNMMI Research

JF - EJNMMI Research

SN - 2191-219X

IS - 1

M1 - 17

ER -

Alves IL, Vállez García D, Parente A, Doorduin J, Dierckx R, Marques da Silva AM et al. Pharmacokinetic modeling of [11C]flumazenil kinetics in the rat brain. EJNMMI Research. 2017 Dec;7(1). 17. https://doi.org/10.1186/s13550-017-0265-4